| 摘要 |
PURPOSE:To prevent formation of pinhole and a nonplating area on the surface of a steel material by imparting ultrasonic vibration to the surface of the steel material immersed in a plating bath from an ultrasonic vibration tip. CONSTITUTION:A steel plate 1 comprising Si killed steel, Si-Al killed steel or high tensile steel is immersed in a plating bath 3 based on molten sinc, molten aluminum or molten lead-tin alloy from a snout 2 and transferred upwardly through sink rollers 4, 5. On both sides of the steel plate 1 in the plating bath 3, ultrasonic vibration tips 8, 10 attached to ultrasonic vibration elements 9, 11 are arranged and ultrasonic vibration is imparted to a surface of the steel plate 1. Leading ends of the tips 8, 10 are arranged at a distance within 10mm. from a surface of the steel plate 1 and, to vibration surfaces of the leading ends of said tips 8, 10, ultrasonic vibration of 1-20w/cm<2> is applied. Further, ultrasonic vibration is imparted to a surface of the steel plate for at least 0.01sec and the tips 8, 10 are arranged so as to cover a total width of the steel plate 1 to be plated. |
